The instant invention relates to surface treating machines, and more particularly to clamps for power driven devices or tools adapted to be manipulated over a surface to be treated for sanding, grinding, polishing, or buffing.
Since the most common use of such surface treating devices is with respect to sanding such surface to be treated, it is usual to refer to such devices as power sanders, although obviously they can be used for other than sanding operations. In the ensuing description and claims, when reference is made to a power sander, it is intended to connote broadly surface treating devices.
In surface treating machines, of which perhaps the most important is a sanding machine, the portable electric sander has become very popular in recent years. There is hardly an adult person today who has not had occasion to use a sander in some form or other for treating a surface, whether it be the surface of a piece of furniture or some other project. As a result of the "do-it-yourself" trend, there has been a tremendous increase in the demand for portable electric sanders, and there have been extensively sold on the market several types of these sanders, among which are the purely vibratory sander, the rotary disk type sander, the belt type sander, the orbital sander, dual motion (orbital and vibratory) sanders, and others. Of the several types of sanders, the orbital, the vibratory and the dual motion sanders offer the greatest utility for all-around work, and the present invention is particularly concerned with these sanders.
A surface treating machine such as an electric sander requires simple and readily actuatable means for releasing and securing the sandpaper to the machine. In any particular sanding operation, it may be desirable to start the surface treating machine with a coarse sandpaper, followed by a medium and then a fine paper, and this action may be followed by a waxing or polishing operation using the same surface treating machine. Obviously, this requires a mechanism for quickly and easily attaching and releasing sandpaper or other surface treating material, and it would be desirable to provide a locking device which easily clamps any form of abrasive such as sandpaper tightly thereto regardless of the thickness of the abrasive paper and without the requirement of any tools.
The prior art abounds with clamping devices for vibratory and orbital sanders, including several overcenter locking devices. However, most of the overcenter clamping devices include spring members, thereby complicating assembly of the sander and requiring considerable effort to lock and release the sandpaper. The instant invention overcomes the problems associated with prior art over-center clamping devices by providing an over-center clamping device which can be easily assembled without any spring tension and which is easily moved into a locking position to clamp the sandpaper tightly.